Printing paper and process of making the same



Dec. 19, 1961 D. D. HINRICHS ETAL 3,013,932

PRINTING PAPER AND PROCESS OF MAKING THE SAME Filed Jan. 14, 1958NON-WOODY LIGNOCELLULOSE, E. G. BAGASSE MIX WITH AN AQUEOUS SOLUTION OFAN ALKALI METAL HYDROXIDE AND/OR ALKALINE EARTH METAL HYDROXIDE HAVING ApH OF AT LEAST I2, THE RESULTING MIXTURE HAVING A L/OUOR'LIGNOCELLULOSERATIO OF FROM 2-! TO 100-! MAINTAIN THE MIXTURE AT BETWEEN 50 AND 250 EUNTIL THE L/GNOCELLULOSE HA5 CONSUMED FROM I"7% BY WEIGHT OF HYDROXIDE(EXPRESSED AS NaOHI. DRY L/GNOCELLULOSE BASIS, AND HAS BEEN SOAKED ANDSOFTENED, BUT NOT SUBSTANTIALLY DEL/GNIFIED MECHANICALLY DEF/BER THESOAKED L/GNOCELLULOSE MECHANICAL-TYPE, NON-WOOD) LIGNOCELLULOSE PULP MIXIF DES/RED WITH FROM I'SOZ, BY WEIGHT DRY I BASIS OF CHEMICALPAPERMAK/NG PULP FORM MIXTURE INTO A PAPER SHEET PRIN TING PA PER PRODUCT DELMER D. HINRICHS. FRED L. SCHMIDT.

JAMES D. WETHERN,

INVENTORS A TTORNE Y 3,tll3,%2 PRENTENG BAYER AND PRGQESS OF MAKENG THESAME Delhi-er i). Hinrichs, Portland, Greg, and Fred ii.

Etchmidt and James D. Wethern, Carnas,Wash., assiguors of one-half toHawaiian Development Conapany, Ltd, Honolulu, Hawaii, a corporation ofHawaii, and one-half to Crown Zellerhach Corporation, San Francisco,CaiitZ, a corporation of Nevada Filed den. 14-, 1953, Ser. No. 708,84115 @laims. (Ci. 162-11) This invention relates to paper productsespecially adapted for use as printing paper, and to a process formaking such products. More specifically, it relates to printing paperssuch as newsprint and book paper which contain in lieu of groundwoodpulp a substantial proportion of mechanical-type pulp derived fromfibrous, non-woody, lignocellulose plant material, and to a process ofmaking such papers. I i

As is well known, newsprint-type printing paper conventionally containsfrom 75-90% by weight groundwood and from 25% of a chemical wood pulp.The groundwood pulp supplies the required opacity, smoothness,resiliency and bulk to the paper, while the chemical wood pulp providesthe necessary strength. However, the high consumption of newsprint madeby present processes requires enormous quantities of pulpwood andresults in the depletion of the forests, particularly with respect topreferred softwood species employed in the manufacture of groundwood.

It accordingly is the general object of this invention to provide aprinting paper made entirely from non-woody lignocellulose pulpavailable at low cost in large quantities, the printing paper productbeing characterized by superior opacity, bulk, strength, and printingqualities, and to provide a process for the manufacture of such a paper.

It is another important object of the present invention to provide amechanical-type, non-woody, lignocellulose pulp which may be employedper se in the production of newsprint or other printing paper ofcommercial quality without the inclusion of any proportion whatsoever ofchemical wood pulp, and to provide a process of making such a pulp.

it is the essence of the present invention that newsprint or otherprinting papers may be made without groundwood, using instead amechanical-type pulp made from non-woody lignocellulose. In executingthe present invention, the non-woody lignocellulose is wilted. andsoftened in an alkaline hydroxide solution without being substantiallydelignified. It then is mechanically defibered. By controlling thereaction conditions as described herein, a pulp is produced which may beused as a replacement for groundwood, or even employed per se in theproduction of a commercial grade printing paper without the inclusion ofpulps of other classes.

Considering the foregoing in greater detail:

The non-woody mechanical-type pulp which is the essential constituent ofthepresently described printing paper may be derived from fibrous,non-woody, lignocellulose plant material such as whole or depithedbagasse, straws, grasses and the like, preferably bagasse, or wheatstraw. For those non-woody lignocellulose materials such as bagassewhich inherently contain pith, substantial removal of the pith by anysuitable procedure is desirable to improve paper machine operations,pulp quality, and pulp handling charcteristics.

As is apparent from the accompanying flow plan, in converting thefibrous raw materials of the foregoing classes into mechanical-type pulpby the presently described procedure, the material first is reduced tosmall 3,13,93 2 Patented Dec. 19, 1961,

pieces, if desired, and then placed in a suitable vessel conraining anaqueous solution of an alkaline hydroxide comprising essentially atleast one member of the group consisting of the alkali-metal hydroxidesand alkalineearth metal hydroxides. Examples are sodium hydroxide,potassium hydroxide, lithium hydroxide, calcium hydroxide, bariumhydroxide, and strontium hydroxide. These may be used singly or inadmixture with each other. Sodium hydroxide is a preferred member of thegroup. Bleaching agents and other chemicals useful in impartingdesirable properties to lignocellulosepulps may be included in theliquor as desired.

The foregoing alkaline hydroxides are employed in amount suflicient toproduce a liquor of the desired concentration, Le. a concentrationsufficient to soak and soften the lignocellulose to the desired extentunder the selected reaction conditions. In general, a liquor containingfrom 0.1 to 25%, preferably from 0.2 to 3% by weight of the hydroxide,calculated as NaOH may be used. A sufficient quantity of the liquor isemployed toether with the non-woody lignocellulose to produce a mixturehaving a liquor-lignocellulose ratio of from 2:1 to :1, preferably from4:1 to 12:1.

The alkaline hydroxide liquor employed should have a pH of at least 12before mixing with the lignoeellulose. This makes possible theproduction of a pulp having sufiicient strength to be used in themanufacture of printing papers without the inclusion of any chemicalpulp whatsoever.

The bagasse or other non-woody lignocellulose is treated with a liquorhaving the indicated characteristics at a temperature which lies broadlybetween 50 and 250 F., preferably between 156 F. and the boiling pointof the liquor at normal atmospheric pressure. The treatment is continuedfor a time suflicient merely to soften and wilt the lignocellulosewithout causing any substantial delig nification thereof. In otherwords, it is carried on until the lignocellulose has consumed only from17%, preferably from 36%, of its own dry weight of the alkalinehydroxide content of the liquor.

The duration of treatment is determined by such factors as the identityof the lignocellulose, the-concentration of the liquor, theliquor-lignocellulose ratio, and thetemperature. In general, however,where the other reaction conditions are as indicated above, a reactiontime at temperature of from 5 to at least minutes, preferably from 30-75minutes, will be required, the longer reaction times being employed withthe lower temperatures and vice versa.

Although a batch process may be used for" soaking the lignocellulose, itis preferred in commercial practice to carry out this operationcontinuously. Thus, the lignocellulose may be passed continuously bysuitable conveying apparatus through a tank containing the alkalinehydroxide liquor at a rate calculated to provide the necessary retentiontime. Additional alkaline hydroxide is introduced into the tank asnecessary to maintain the re quired concentration.

After the lignocellulose has passed through the tank, it may be drainedon a suitable conveyor, the drainings being returned to the tank.Alternatively, the material may be passed through a screw press, squeezerolls, or washing devices for removal of the residual liquor. The liquorthus removed may be returned to the tank, care being exercised toprevent undue liquor dilution. Such a system has the advantage ofreducing chemical loss, since any liquor recovered is reusable.

The softened and wiltedlignocellulose is fed, preferably metered, into asingle disc (SproutWaldron) refiner, a double disc (Bauer) refiner, amultidisc (Reisten) refiner, rodrnill, ball mill, hammermill, or otherdefibering apparatus, the operation of which is characterized primarilyby rubbing and crushing the lignocellulose as opposed to cutting it,thereby keeping the fiber length at a maximum value. If desired, a screwpress may be used in conjunction with any of the above defiberingmachines ahead of the defibering elements.

For best results, the defibering consistency should be from l30%,preferably from 4-10%. The defibering temperature should be from 70-220F. preferably from 170-212 F. The feed rate, refiner plate clearance andrefiner plate pattern are selected so that 1 to passes, preferably onepass, through the refiner will give a mechanical pulp of the desiredfreeness while using the maximum power of the refiner.

Maintaining a high power loading on the refiner results in a lower powerconsumption per ton of pulp produced. Thus the refiner plate clearanceshould be so adjusted that high power loading is maintained duringrefining, and a well-defibered pulp product is obtained at a desiredfreeness level.

The refined pulp resembles groundwood in many respects. It has afreeness of 5-300, preferably 50-150 cc. CSF (Canadian standardfreeness) and a brightness of 30-55% GERS (General Electric recordingspectrophotometer) at 460 m (millimicrons). It may be used directly inthe manufacture of the herein described printing paper, but preferablyis diluted to a consistency of from 0.5-3% and screened to removeoversize fiber particles. After screening, it may, if necessary, bediluted to about 0.5% consistency and pumped through a centrifugalcleaner for removal of any remaining dirt particles or shives. Theaccepted pulp may be used at once in the manufacture of paper, or it maybe partially dewatered into a wet-lap and stored until used.

If it is desired to increase the pulp brightness, the pulp may bebleached easily using conventional bleaching agents in amount suflicientto attain the desired brightness value. However, it is a particularfeature of the invention that the pulp may be bleached in two stageswith a hydrosulfite bleaching agent to a degree of brightness which ismarkedly higher than that which is attained by conventional one stagehydrosulfite bleaching of lignocellulose pulps. The first of thesestages occurs during the soaking of the lignocellulose with alkalinehydroxide, using part of the hydrosulfite bleaching agent. The secondoccurs after defibering, using the remainder of the hydrosulfite.

The hydrosulfite bleaching agent may comprise any of the alkali metalhydrosulfites, preferably sodium hydrosulfite, and/ or zinchydrosulfite. These may be used with or without various bleaching aidssuch as the alkali metal polyphosphates.

Although the amount of hydrosulfite bleaching agent to be used issomewhat variable, in general an overall use of from 0.2 to 5%,preferably 0.5 to 2%, of hydrosulfite, calculated as Na S O oven drylignocellulose basis, may be employed. From 5 to 95%, preferably 40-60%of the total amount of hydrosulfite is employed in the first or soakingstage and from 955%, preferably from 60-40%, by weight in the second orpost defibering stage, the conditions prevailing during the secondbleaching stage being substantially the same as those conventionallyemployed when bleaching pulps with hydrosulfite bleaching agents.

Where a chemical cellulose pulp is employed in conjunction with the pulpof the present invention, it may be derived from any species ofconiferous pulpwood, such as spruce, hemlock, fir, pine and others;deciduous pulpwood such as poplar, birch, alder, gum and others; as wellas from non-woody lignocellulose plant materials suitable forpapermaking, such as cereal straws, bagasse, cornstalks, grasses, andthe like.

These various lignocellulose materials may be converted into pulp inaccordance with any of the conventional chemical pulping procedures inwhich lignocellulose is digested, usually under pressure, with anaqueous liquor containing the selected pulping agent. Such liquorscomprise those employed in the kraft, soda, acid sulfite, neutralsulfite, chlorine-soda and other well known processes. In preparing theherein described printing paper, however, it is preferred to employ thechemical coniferous wood pulps and/or the kraft or soda nonwoodylignocellulose pulps, particularly the kraft or soda bagasse and wheatstraw pulps.

The foregoing chemical pulps may be employed either singly or inadmixture with each other and may be subjected to preliminary treatmentsif desirable or necessary to improve their paperinaking qualities. Thusthey may be bleached to increase their brightness to a level determinedby the brightness desired in the final paper product. Also they may bebeaten and hydrated in commercial beaters or pulp refiners, particularlyif they have been derived from wood, in order to enhance their strengthand forming qualities.

In preparing the herein described papermaking furnish, the non-woodymechanicabtype lignocellulose pulp prepared in the foregoing manner may,if desired, for added strength be mixed with any of the above describedchemical pulps using broadly from l50%, by weight dry basis of thelatter. The two pulps may be mixed together in a convenient manner, suchas for example, by addition of lap pulp to the beater with the rollraised, or by simple fluid mixing in slush pulp aqueous systems. After asubstantially uniform fibrous slurry has been produced, it is run over aconventional paper machine in the normal manner for the production ofprinting papers.

In typical examples illustrating the presently described procedure, aquantity of raw, non-woody lignocellulose was placed in asteam-jacketed, open kettle and the indicated quantity of alkalineliquor added. The temperature of the charge was elevated to the desiredlevel by indirect steam heating over a 10 minute interval. At theconclusion of the reaction period, the spent alkaline liquor was drainedoff and the wilted and softened lignocellulose metered into a rotatingdisc refiner by means of a moving conveyor belt and spike-tooth feeder.Four pulp samples were thus prepared, three from substantially depithedbagasse (samples 1, 2 and 3) and one from wheat straw (sample 4). Thesoaking and refining conditions are summarized in Table I below:

Table I Sample 1 Sample 2 Sample 3 Sample 4 (Bagasse) (Bagasse)(Bagassc) (Wheat Straw) Soaking conditions:

Alkaline liquor pH l2. 7 12. 7 12. 5 l2. 5 Liquor to dry lignocelluloseratio 12. 4:1 12.411 12.4:1 10:1 Temperature, F 170 212 212 212 Tune attemperature,

mm 60 60 30 00 Sodium hydroxide consumption on oven dry lignocellulose,percent by Wt 5 5 5 4 Bleaching agent present No N 0 Yes No Refiningconditions:

Consistency, percent- 8 5 8 6 Temperature, F-.. 170 212 212 160 Numberof passes". 1 1 2 2 Test Results:

Power usage, HP days/ ton refined lignocellulose 38 37 52 20 Freeness,cc. OSF 63 41 60 136 Bursting Strength, r-

cent 25 32 30 24 Tearing Resistance 0.58 0. 62 0. 58 0. 54 Breakinglength, meters 3, 800 4, 000 4,100 3, 240 Apparent Density, g./cc 0. 430. 50 0. 44 0. 38 Brightness, GERS at 460 mu, percent 34 38 45 38Opacity, percent 92 92 95 94 Yield, percent on w lignocellulose 86 83 851 0.5% NagSiOi and 0.25% N rrow on oven dry bagasse.

The mechanical-type pulps produced by the foregoing procedures (samples1 and 2) were similar in properties to commercial groundwood pulps. Theywere used in the preparation of a series of printing papers both aloneand mixed With chemical-type pulps in various proportions. Thecompositions of the papers thus produced and their properties areindicated in Table II below, wherein the terminology is thatconventional to paper testing and wherein all of the paper samples had abasis weight of 32 lbs/ream (24 x 36/500). 10 manufacture of groundwood.

Table II Standard U.S. Newsprint, Percent 100 0 0 0 0 0 O 0 0 0 0 0 O 0Mechanical-type Bagasse Pulp (Sample 1), Percent 0 100 0 0 0 0 0 O 0 0 090 75 0 0 llleehanical-type Bagasse Pulp (Sample 2), Pen A 0 0 100 90 7550 90 75 50 90 75 0 0 90 75 0 0 25 1 50 10 25 2 50 10 25 1O 3 25 10 4 25Bull 96-110 110 98 90 94 88 98 96 92 96 96 105 95 96 95 Burst, Percent22 26 25 32 26 29 38 25 28 37 27 35 32 50 28 40 Tear, g./sheet MachineDirection -17 15 14 17 22 28 18 22 30 19 26 20 24 26 41 Tensile. lbs/ Ainch Ma- .ch'L'icDircctiolL 4.0-4.5 3.6 3.2 3.7 3.9 4.3 3.6 3.9 4.5 4.04.3 4.2 6.4 4.0 4.6 Opacity, Icrccnt 86-91 92 92 S9 89 85 89 87 84 88 8786 82 89 86 1 Bleached kraft bagasse pulp. Bleached deciduous chemicalwood pulp (Cottonwood kraft). 3 Unbleached coniferous chemical wood pulp(hemlock sulfite). 4 Semi-bleached kraft coniferous wood pulp.

To test further the bleachability of the bagasse pulp I Having thusdescribed our invention in preferred ems'aznple 3 (Table I) which hadbeen soaked with alkaline 30 bodiments, We claim:

hydroxide including -a proportion of sodium hydrosulfite bleaching agentand thereafter defibered, was Washed with water and its pH adjusted to5.5 with acetic acid. It then was treated with further proportions ofsodium hydrosulfite and the brightness of the resulting pulp determined.The results are given in Table III below:

Bagasse soaked 30 min. with 5% NaOH at 212 F. and defibered but notbleached.

To test the elfect of incorporating the above bleached pulp in paper,the pulp designated sample 6 in Table III was mixed with bleached kraftbagasse pulp and run into paper sheets of selected compositon with theresults indicated below in Table IV:

Table IV Bleached Mechanical-type Bagasse Pulp,

Percent 100 90 75 50 Bleached Kraft Bacasse Pulp, Percent" 0 10 25 50Basis Weight, 24 X 36/500 32 32 32 32 Bulk Index 94 91 88 85 Burst,Percent 33 37 42 Tear, g. em./sheet 17 21 27 Tensile, lbs./% in 3. 7 4.1 4. 5 Brightness, GERS, 57 58 60 Opacity, Percent 92 90 87 Accordinglyit will be apparent that by the practice of the present invention, acommercially acceptable, printing type paper which is bleachable to ahigh degree of brightness may be produced Without the use of thegroundwood pulp normally required to provide bulk, opacity, smoothnessand resiliency. Instead, a mechanically disintegrated, non-woodylignocellulose pulp is employed to provide these qualities, as well asall ormost of the inherent strength of the paper.

1. The process of making printing paper which comprises forming amixture of at least one non-woody lignocellulose selected from the groupconsisting of bagasse, straws and grasses, together with an aqueousliquor containing from 0.1 to 25% by Weight of at least one member ofthe-group consisting of the alkali metal hydroxides and the alkalineearth metal hydroxides and'having a pH of at least 12, said mixturehaving a liquor-lignocellulose ratio, dry lignocellulose basis, of from2:1 to :1; softening the lignocellulose by maintaining the mixture at atemperature of between 50 F. and 250 F. until the lignocellulose hasconsumed from 1 to 7% of its oven-dry Weight of the hydroxide,calculated as NaOH, While retaining substantially all of its originallignin content; mechanically defibering the softened lignocellulose toform a mechanical-type papermaking pulp of high lignin content and goodprinting qualities; and running the pulp 7 into paper.

2. The printing paper product of the process of claim 1.

3. The process of claim 1, wherein 1e non-Woody lignocellulose isbagasse.

4. The process of claim 1 including the step of bleaching the non-woodylignocellulose with from 0.2 to 5% by weight of at least one bleachingagent selected from the group consisting of zinc hydrosulfite and thealkali metal hydrosulfites, dry lignocellulose basis, from 5 to 95% byweight of the total amount of the hydrosulfite being applied to thelignocellulose while treating it with the alkaline liquor and theremainder being applied to the mechanically defibered lignocellulosepulp.

5. The process of making printing paper which comprises forming amixture of bagasse Withan aqueous liquor containing from 0.1 to 25% byweight of sodium hydroxide and having a pH .of at least 12, said mixturehaving a liquor-bagasse ratio, dry bagasse basis, of from 4:1 to 12:1;softening the bagasse by maintaining the mixture at a temperature ofbetween F. and the boiling point thereof until the bagasse has consumedfrom 3 to 6% of its dry Weight of the hydroxide, while retain ingsubstantially all of its original lignin content; mechanicallydefibering the softened bagasse to form a mechanicaltype papermakingpulp of high lignin content and good printing qualities; and running thepulp into paper. I

6. The printing paper product of the process ofrclaim 5. I

7. The process of claim 5 including the step of bleach- 7 ing thebagasse with from 0.2 to by weight, dry bagasse basis of sodiumhydrosulfite, from 5 to 95% by weight of the total amount ofhydrosulfite being applied to the bagasse while soaking it with thesodium hydroxide, and the remainder being applied to the mechanicallydefibered bagasse pulp.

8. The process of making papermaking pulp which comprises forming amixture of at least one non-woody lignocellulose selected from the groupconsisting of bagasse, straws and grasses, together with an aqueousliquor containing from 0.1 to by weight of at least one member of thegroup consisting of the alkali metal hydroxides and the alkaline earthmetal hydroxides and having a pH of at least 12, said mixture having aliquorlignocellulose ratio, dry lignocellulose basis, of from 2:1 to100:1; softening the lignocellulose by maintaining the mixture at atemperature of between 50 F. and 250 F. until the lignocellulose hasconsumed from 1 to 7% of its oven-dry weight of the hydroxide,calculated as NaOH, while retaining substantially all of its originallignin content; and mechanically delibering the softened lignocelluloseto form a mechanical-type papermaking pulp of high lignin content andgood printing qualities.

9. A sheet of pulp produced by the process of claim 8.

10. The process of claim 8 wherein the non-woody lignocellulose isbagasse.

11. The process of claim 8 including the step of bleaching the non-woodylignocellulose with from 0.2 to 5% by weight of at least one bleachingagent selected from the group consisting of zinc hydrosulfite and thealkali metal hydrosulfites, dry lignocellulose basis, from 5 to 95% byweight of the total amount of the hydrosulfite being applied to thelignocellulose while treating it with the alkaline liquor and theremainder being applied to the mechanically defibered lignocellulosepulp.

12. The process of making papermaking pulp which comprises forming amixture of bagasse and an aqueous liquor containing from 0.1 to 25% byweight of sodium hydroxide and having a pH of at least 12, said mixturehaving a liquor-bagasse ratio, dry bagasse basis, of from 2:1 to 100:1;softening the bagasse by maintaining the mixture at a temperature ofbetween 50 F. and 250 F. until the bagasse has consumed from 1 to 7% ofits ovendry weight of the hydroxide while retaining substantially all ofits original lignin content; and mechanically dea fibering the softenedbagasse to form a mechanical-type papermaking pulp of high lignincontent and good printing qualities.

13. The process of making paperrnaking pulp which comprises forming amixture of bagasse and an aqueous liquor containing from 0.1 to 25 byweight of sodium hydroxide and having a pH of at least 12, said mixturehaving a liquor-bagasse ratio, dry bagasse basis, of from 4:1 to 12:1;softening the bagasse by maintaining the mixture at a temperature ofbetween 150 F. and the boiling point of the liquor until the bagasse hasconsumed from 3 to 6% of its oven-dry weight of the hydroxide, Whileretaining substantially all of its original lignin content; andmechanically defibering the softened bagasse to form a mechanical-typepapermaking pulp of high lignin content and good printing qualities.

14. A sheet of pulp produced by the process of claim 13.

15. The process of claim 13 including the step of bleaching the bagassewith from 0.2 to 5% by weight, dry bagasse basis, of sodiumhydrosulfite, from 5 to by weight of the total amount of hydrosulfitebeing applied to the bagasse while soaking it with the NaOH liquor, andthe remainder being applied to the mechanically defibered bagasse pulp.

References Cited in the file of this patent UNITED STATES PATENTS1,597,880 Gregor Aug. 31, 1926 1,929,145 Lenher Oct, 3, 1933 2,425,024Beveridge Aug. 5, 1947 2,708,160 Aronovsky May 10, 1955 2,805,156 PayneSept. 3, 1957 OTHER REFERENCES Ser. No. 122,076, Gunther (A.P.C.),published May Litkenhons: Bagasse AB, a Source of Pulp, from theChemuragic Digest, pp. 169, 171-178, vol. 1V, No. 10, May 31, 1945.

Wells: Utilization of Cornstalks in the Manufacture of Paper andPaperboard, from TAPPI, Sec., pp. 163-169, Apr. 15, 1943.

USDA, Commercial Uses of Sugarcane Bagasse Studied, USDA, 2914-55, 1 p.,Nov. 9, 1955.

12. THE PROCESS OF MAKING PAPERMAKING PULP WHICH COMPRISES FORMING AMIXTURE OF BAGASSE AND AN AQUEOUS LIQUOR CONTAINING FROM 0.1 TO 25% BYWEIGHT OF SODIUM HYDROXIDE AND HAVING A PH OF AT LEAST 12, SAID MIXTUREHAVING A LIQUOR-BAGASSE BY MAINTAINING THE 2:1 TO 100:1 SOFTENING THEBAGASSE BY MAINTAINING THE MIXTURE AT A TEMPERATURE OF BETWEEN 50*F. AND250*F. UNTIL THE BAGASSE HAS CONSUMED FROM 1 TO 7% OF ITS OVENDRY WEIGHTOF THE HYDROXIDE WHILE RETAINING SUBSTANTIALLY ALL OF ITS ORIGINALLIGNIN CONTENT, AND MECHANICALLY DEFIBERING THE SOFTENED BAGASSE TO FORMA MECHANICAL-TYPE PAPERMAKING PULP OF HIGH LIGNIN CONTENT AND GOODPRINTING QUALITIES.